Synthesis of 2-ethylhexyl-2-ethylhexanoate catalyzed by immobilized lipase in n-hexane: A kinetic study

A direct esterification reaction for the synthesis of 2-ethylhexyl-2-ethylhexanoate from 2-ethylhexanoic acid and 2-ethyl-1-hexanol in n-hexane as solvent, and Novozym 435, as catalyst, has been carried out. The effect of concentrations of 2-ethylhexyl-2-ethylhexanoate, water, 2-ethylhexanoic acid and 2-ethyl-1-hexanol on ester yield, the initial forward esterification reaction and the reverse reaction rates have been investigated. The experimental results show that the esterification reaction proceeds with a Ping-Pong Bi-Bi mechanism and that 2-ethylhexanoic acid inhibits the reaction.Kinetic parameters were calculated based on this model as follows: Rmax = 37.59 mmol h−1 g−1, KmAl = 1.51 M, KmAc = 0.78 M, KiAc = 1.55 M. The calculated parameters were used to estimate the theoretical initial reaction rate. The calculated initial reaction rates from kinetic parameters for concentrations of less than 0.1 M 2-ethylhexanoic acid show good agreements with the experimental data.